There has for years existed an industry of providing bracelet devices to electrically ground--through a grounding circuit--certain workers in the field of semiconductor components and circuits. This prevents the static electricity, generated by the workers, from damaging the components or circuits being worked on. A complete grounding circuit is described and illustrated in U.S. Pat. No. 4,373,175, which is hereby incorporated by reference herein.
Two types of bracelets are conventionally made by manufacturers in the indicated field. One employs conductive fibrous material, woven or otherwise, as the band or strap portion of the bracelet. The other employs an expansible metal-link wristband component. The present invention relates to the latter type of device.
At the present time there are approximately five American manufacturers of antistatic bracelets incorporating expansible metal-link wristbands. Such manufacturers buy individual wristbands from Textron Inc. of Providence, R.I. Textron manufactures the wristbands under patents including U.S. Pat. Nos. 4,096,688 and 4,375,713, that are hereby incorporated by reference herein.
The particular metal-link band material now primarily employed in the indicated antistatic industry may be obtained from Textron under its number 01802561, being designated "STATIC SKEL", and trademarked SPEIDEL. The last-indicated component is specially made by Textron for the antistatic bracelet industry, and includes an upper layer of metal links to which is laminated a thin film or sheet of polyvinylfluoride synthetic resin, thus providing insulation to protect the wearer. It is emphasized that the wearer should be protected against electric shock, and this is done, relative to the indicated bracelet or wristband material, by effectively insulating the upper layer of metal links.
The American companies in the metal wristband industry buy the individual wristbands from Textron in three discrete sizes--small, medium and large. At each end of each wristband is a metal loop or hollow cylinder. The companies employ these metal loops to secure the wristbands in nonadjustable manner to opposite ends of a connector element.
It follows that each bracelet manufacturer (and distributors therefor) must stock three sizes of the bracelets, so that they are readily available to the customer. It is also pointed out that "small-medium-large" leaves a great deal to be desired relative to comfort to the user. For certain sizes of wrists, "small" may be somewhat small while "medium" may be somewhat large. Furthermore, the user may desire that different sizes be employed at different times, for example when the temperature changes or when the worker is in different states of mind.